George ii



M R m NA IE H TC I Hm Wm L HE (No Model.)

No. 579,469. Patented Mar. 23, 1897.

INVE'NTUR I i, AA ZWMM ATT DRNEY- UNITED STATES Farsnr lrEORGE ll.lVlll'lTlNGllAM, OF BALTlMORE, MARYLAND.

SPECIFICATION forming part of Letters Patent 579,459, dated March 28,1897.

Application filed January 30, 1896. Serial lie. 577,859. (No model.)

To all whom, it may concern.-

Be it known that I, GEORGE H. 'WHITrrNG HAM, a citizen of the UnitedStates, residing at Baltimore, in the State of lliaryland, have inventedcertain new and useful improve ments in Electric Heaters, of which thefollowing is a specification.

My invention relates to an improvement in electric heaters, and has forits object to pro vide a tubular heater in which the resistancewireshall have its entrance and exit the same end of the tube and haveefficient means for relieving the resistance-wire of the heat generatedby the passage of the electric current.

For a full understanding of the invention reference is made to theaccompanying drawings, in which- Figure 1 is a longitudinal centralsection showing the resistance-coils and two parallel glass tubes in thecasing and the insulating heat-conducting filler. Fig. 2 shows acrosssection. Fig. 3 is a longitudinal section showing a modification inthe construction of the two glass tubes. Fig. 4 shows a cross-section ofthe modified form seen in Fig. 4. Fig. 5 shows the heater in the form ofa coil.

Referring to Figs. 1 and 2 of the drawings, the letterA indicates theresistance-wire, and D a'tubular casing, of iron or other materialsuitable for rapidly radiating heat, and which incloses theresistance-wire and is closed at its ends by screw-caps cl d. Theresistance A enters the tube and also comes out at the same end. I

In the simplest form of my device there is within the tubular casing Dand surrounding the resistance-wire a plurality of glass tubes shorterthan the interior of the casin and a filling of clear loose sand it,which is employed as a heat-conducting medium between the wire and theouter casing and at the same time electrically insulates the wiretherefrom. By this construe tion the heat of the wire is rapidlyconducted to the outer casing, and the latter has its exterior surfaceexposed for radiation of the heat. It will be seen that theradiating-surface of the tubular easin g D is greatly larger than thesurface of the wire it incloses.

The cap d at one end of the tubular ea. ing has two insulating bushingsor plugs c, and the wire passes through one of these in en tering andthrough the other in coming out. Where the wire passes through theinsulation 8, it is larger, to increase the conducting capaeity.

I employ two tubes 9 g, extending longitudinally of the exterior tube D.These serve to separate and electricallyinsulate the two stretches ofresistance-wire inelosed in the radiating-tube D. In Figs. 1 and 2 thetwo glass tubes are side by side, parallel, and the entrance stretch 1,of wire, passes through the tube g and at the end crosses over, as at9;, to the other tube g, and the exit stretch 53 passes through thissecond tube. Thus the wire which enters the radiating-tube at one endcontinues to the other end and then returns to the same end, where itenters. Thereby there is a double-resistance wire inclosed in the tubeD, and the device is adapted and is more convenient for use in certainsituations. The sand 72. is filled in both glass tubes, and also betweenthe glass tubes and the inclosing tube D, so as to form continuousheat-conducting medium from the resistancewire to the said outercasing-tube.

The modification shown in Figs. 3 and employs two glass tubes g parallelwith each other, but here the tubes are of different size, in order thatthe smaller tube may extend through the larger tube 9 In this form theentrance stretch 1, of wire, is coiled around the small tube, andtherefore is in the larger tube or between the small and the large tubeAt the end the wire crosses, as at 0;, from the outside to the innerside of the tube, and the exit stretch 2 in this case extends straightthrough the inner tube back to the entrance end.

The ends of the tube D may be closed in any suitable manner.

A tube D,'filled with sand packed in and havin g glass tubes throughwhich the resistancewire passes, sand being filled within as well asaround the glass tubes, may be bent or coiled, as desired. This isillustrated in Fig. 5. During this operation of bending the metal tubethe glass tubes will be broken into small particles, but these particleswill still retain the tubular form and have the same relative positionwith respect to the sandfiller.

It will be seen that the resistance-wire is sustained in the tubularradiating-casing and prevented from sagging independent of both thefiller and of said ease.

Having thus described in y invention what I claim as new, and desire tosecure by Letters Patent, is

In an electric heater, the combination of a tubular easing; means forclosing both ends thereof; a plurality of glass tubes shorter than theinterior of the easing and situated. therein; a resistance-wire enteringone end of the casing, extending through one of the glass tubes andreturning through another of the tubes and passing out of the casing atthe same end at which it enters; and a suit- 15 able granulated fillerplaced in the spaces in and around the glass tubes.

In testimony whereof I al'tix. my signature in the presence of twoWitnesses.

GEORGE 1i. \Vll'l'l" INGHAM.

Witnesses:

CHARLES 1 MANN, J11, C. CALVERT ll'l'NEs.

